Grapefruit Seed Extract-All Purpose Liquid Concentrate 32 oz. Bottle. Nutribiotic® Liquid Concentrate contains CITRICIDAL®. CITRICIDAL; is a natural quaternary compound synthesized from the seed and pulp of certified organically grown grapefruit. The manufacturing process converts grapefruit bioflavonoid (polyphenolics); into an extremely potent compound that has been proven highly effective in numerous applications. CITRICIDAL is used by healthcare professionals worldwide as nutritional support for individuals with certain health concerns. Each bottle comes with instructions for use.